BBC Sport examines some of the key themes before Sunday's match (14:00 GMT), with bottom side Sunderland hosting in-form Chelsea.

Sunday marks 168 days since Sunderland beat Chelsea on the final day of the season, securing European qualification for the first time in 53 years, but the Wearsiders' fortunes have declined dramatically since then.

Last weekend's 3-1 defeat at Coventry City kept the Black Cats bottom of the table and increased the pressure on head coach Regis le Bris. However, club sources have since told BBC Sport the Frenchman will be given more time to halt the slide.

Le Bris' side spectacularly exceeded expectations by finishing seventh last term but this season have been profligate in attack and vulnerable at the back.

While Sunderland rank 10th for expected goals, they have underperformed their xG by six, making them the Premier League's second most wasteful finishers.

At the other end, they have gone from allowing the second-lowest xG per shot last season to the second highest in the current campaign. They are not conceding notably more attempts, but opponents are being afforded the time and space to shoot from more dangerous positions.

That helps explain why Robin Roefs has saved fewer than half of the 33 shots on target he has faced in the Premier League this season - the lowest rate of any goalkeeper to have played more than once.

Chelsea's defeat at the Stadium of Light in May ended their hopes of qualifying for Europe, but the Blues look well set to return to continental competition after an encouraging start under Xabi Alonso. The west London side have won three of their past four Premier League games - as many victories as in their previous 14 matches combined.

Alonso's side rode their luck at times during the first half against Manchester United last weekend, but took control after the break through goals from Morgan Rogers and Cole Palmer.

Rogers has scored six goals since joining from Aston Villa this summer, one more than Palmer. The two players became friends during their time together in Manchester City's academy and have taken little time to rekindle their on-pitch chemistry.

The pair have created 14 chances for each other in the Premier League this season, with Rogers providing 10 shooting opportunities for Palmer, who has returned the favour on four occasions. No other pairing combined for more than nine shots going into this set of fixtures.